Re: [boost] painless currying

Subject: Re: [boost] painless currying
From: Edward Diener (eldiener_at_[hidden])
Date: 2011-09-03 11:15:11

On 9/1/2011 9:40 PM, Paul Mensonides wrote:
> On Thu, 01 Sep 2011 18:23:16 -0400, Edward Diener wrote:
>
>> The remark refers in the resolution above refers to "my reading of the
>> standard" but does not say which standard is being referred to. Is this
>> part of C99 or C++11 ? I have asked about this on the C++ standard NG
>> and am awaiting an answer.
>>
>> I am surprised by the evaluation of "#elif constant expression" when the
>> corrwesponding #if statament is true because it means that #if - #elif
>> is not equivalent to #if - #else - #if in this particular case, and I am
>> sure many C++ programmers would have expected that the two were indeed
>> equivalent.
>
> It doesn't "evaluate" it; it just parses it.  Even in normal code and, in
> most cases, even with dynamically-typed code, the compiler or interpreter
> still has to parse the else-if expressions.

So if I have:

#if 1
#else
nonC++gobbledygook
#endif

The compiler still parses nonC++gobbledygook and issues an error if it 
is invalid C++ code ?

>  Neither C99 or C++98 (or C+
> +11) are particularly clear on this.  To me that means that the solution
> is on the code side rather than requiring a compiler to allow semi-
> unspecified behavior in the short term and to alter the standard if it is
> important enough in the long term.

I admit that I have always thought that an #if - #else - #endif path 
which is not taken can be anything and does not have to be valid C++. 
You seem to be saying otherwise.